Flameproofing composition



United States Patent 2,991,182 FLAMEPROOEIN G COMPOSITION CharleslM.Shaw, Albany, 'Califi, assignor to California Research Corporation,.SanFrancisco, "Calif a corporation of Delaware -N'o Drawing. 'FiledDec. 21,1959, Ser. No. 860,686 3 Claims. (014106-15) This invention relates tonovel compositions for the flameproofing of normally flammable articles.More particularly, theinvention :is concerned with superior new woodflameproofing compositions containing thiophosphorus compounds .andunique combinations thereof.

Wood is employed extensively in many present day structures "because itis often more available andeasier to work ,with .on location thanother'materials. Bridges, telephone ,poles, railroad trestles, loadingdocks and marine ,Wharvesareillustrative of some of the more commonuses.rInrSllCh applications, it is generally desirable to ztreatrthe 'woodwith preservative oils to prevent decay or other deterioration.Unfortunately, .the treated wood structures are :even more susceptibleto damage by fire because ,of the flammable nature of the preservativeoil whichzis cumulative :to the :normal combustibility of the wood.

rEiredamage-js also :a matterof concern inmany inflammable articlesother :than wooden structures. For example, 1cotton and :similar {fibersused in the manufacture 10f cloth such'as :canvas Lfor tents;and tarpaulins are well known for their flammability. Such articles also arecommonly treated with preservatives which add to the normally flammablecharacter of the fibers.

It has now been found that flammable articles are effectivelyflameproofed by impregnation with a superior new composition comprisinga major proportion of liquid vehicle, more particularly a preservativeoil, and atleast by weight of amember of the groups consisting of (1)reaction product of phosphorus pentasulfied :and pinene, (2) zincdialkyl dithiophosphatecontaining from 3 to 8 carbon atoms in each of,the alkyl' groups and ezinc dialkylphenyl dithiophosphate containingfrom .14 to 24 carbon atoms in each of the alkylphenyl groups, and (3)combination of members of each of group (1) :and group (2) saidcombination consisting of from 10 to 90% by Weight of reactionproductandfrom 10 to 90% by weight of zinc dithiophosphate.

The normally inflammable ;nature of wood or other such flammablearticles .isremarkably inhibited by treatment with the flameproofingcompositions of this invention. The unique combination of:thiophosphorus compounds in the compositionsprovides amuchgreater fireretarding efiect than would be expected from the performance of eitherone of the thiophosphorus compounds alone.

The term flameproof" is used in this description in its commonlyaccepted sense and refers to the treatment of .the articleso that ,it,isresistant to the propagation of flame once .the 'ignitionsource has beenremoved. This use is consistent withthe definition of 'the term in theASTM 'standards yearbook for 1944 under Test D626- 4lT.

The liquid :veliicles and preservative oilsof the compositionsaccordingito this invention are primarily forthe purposeof providing asuitable carrier for applying the thiophosphorus composition to thearticle being treated. Aqueous compositions are useful. Preferably,however, the'liguid vehicle is an oil. The oilmay be designed toevaporate and 'leave'the flameproof composition of the phosphoruscompounds as aresidue in the treated article, as in thecaseof'a-lightthinner or petroleum naphtha. It may be designed-to penetrate andserve'asa preservative or it 'may remain largely on the surface and 1serve 2,991,182 Patented July 4, 1961 asa finish or protective coat.other vegetable oils and natural or synthetic resins may be used to formflameproof coatings. Various petroleum andcoal tar derived oils, such ascresols, aromaticpetroleum extracts, medium boiling fuels of the dieseloil and furnace oil type, and heavier fuels, for example, topped'naphthenic crude oil may be used to penetrate andpreserve the articletreated. The wood preservative oils having pesticidal and fungicidalproperties such as creosote and petroleum hydrocarbons containingpentataneously after heating slightly to initiate the reaction.

Usually, the turpentine or other pinene or terpene containing materialis heated to about 200 F. and the phosphorus pentasulfide is addedslowly Wlth stirring. Cooling may be employed if necessary to avoidundesirably high temperatures in excess of 300 F. In the process,addition agents such as aliphatic alcohols, for example, lauryl alcoholmay be combined with the turpentineand phosphorus pentasulfide.

Illustrative thiophosphate compounds for present ,purposes include themetal salts of thiophosphates prepared by the reaction of phosphoruspentasulfide with an aliphatic alcohol or an alkyl phenol. Suchreactions are straightforward and excess unreacted materials are readilyremoved by conventional separation methods, for example, filtration,distillation and the like. The alcohols and phenols, ormixtures-thereof, are usuallyreaeted -with phosphorus pentasulfide attemperatures of from about 200 to 300 F. The suitable aliphatic alcohols-contain from '1 to '16 carbon atoms and ;preferably 3 to 8 carbonatoms. The alkyl'phenols contain from 8 to 24 carbon atoms andpreferably 14 to 24 carbon atoms.

the standpoint of effectiveness and economy of raw materials. The metalsalt of the phosphorus sulfide reaction product is conveniently formedbythe addition of the corresponding metal'oxide to the reaction product..The zinc salts are preferred. No special conditions are required,although heating and stirring are usually employed to effect completereaction.

The'pinene-p'hosphorus sulfide reaction products .and the metaldithiophosphates of the flameproofing compositions, as mentioned above,are generallyknown as'lubi'i-' eating oil additives. They are describedin considerable detail in various texts on lubricating oil additives. Abrief description of such additives is to be found at pages 167 to 178,of Motor Oils and Engine Lubrication by Georgi, published in 1950 byReinhold Publishing "Corporation, New York, New York. So far as isknown, such compounds have not been suggested in the form of the presentcompositions and concentrates, norhave they been proposed for use withpreservative oils as flameproofing compositions.

The combination ofphosphorus pentasulfide and pinene reaction productand the zinc dithiophosphate, as mentioned above, is surprisinglyelfective. It may vary in proportions so long as there is at least 10%by weight of For example, linseed .or

3 Ordinarily, maximum benefit of the combination of additives isobtained with 40 to 60% by weight of each in the combination. V

The phosphorus pentasulfide-pinene reaction product prepared is found togive excellent fire retarding properties to wood in the standard tests,as described below.

The standard crib burning tests show the efiect of the flameproofingcompositions on a field scale. In the crib andfzinc dithiophosphate .andtheir combination in the 5 tests, the treated timber being evaluated isarranged in wood'p'reservat-ive oil are used in minor amounts sufficientthe form of a square crib. The timber is cut from thorto inhibit orretard burning of the treated wood. At least oughly air-seasoned 7 in. x9 in. x 8 ft. Douglas fir cross 5% by weight of the compounds on thebasis of total ties having a moisture content of 11 to 13%. The tiescomposition is. ordinarily desirable, particularly in the are cut intopieces of three sizes: 4% in. x 7' in. x 8 ft. treatment of wood.Usually not more than 20 or 30% rough, 4 in. x 4 in. x 24 in. smooth onfour sides and 2 0f the thiophosphate compounds is required foreifective in. x 4 in. x 2 in. smooth on four sides. The number offlameproofing. pieces of each size treated with the fiameproofer is ap-In'acc ordance with the present invention, concentrates proximatelydouble the number used. The pieces with of the combination ofthiop'hosphorus compounds are also the highest and the lowest retentionsare rejected. The provided as particularly suited for the preparation ofthe 4 A in. x 7 in. pieces are treated in the original 8 it. length.flameproofing compositions from wood preservative oils Before testing, 8inches are cut ofi the ends of each piece that may be available at theparticular time and place of and the remainder is cut in half. Thus, thepieces actualtreatment. These concentrates contain at least 60% by lyburned are 4 /2 x 7 in. by 40 in. The 2 x 4 and 4 x 4 weight of thecombination of phosphorus pentasulfidepieces are treated and burned inthe 24 in. length. pinene reaction product and zinc dithiophosphates.Or- In these tests, a comparison is made by the use of four dinarily,notmore than 90% of the combination is used. different treatments. Thetreatments are: (1) straight The balance of the concentrate is usuallychosen from any creosote, (2) an aqueous solution containing about 8% ofof the typical petroleum hydrocarbon oils such as diesel water solublesalts consisting of 10% diammonium phosfuel, creosote, etc. For presentpurposes, a liquid arophate, 60% ammonium sulfate, 20% sodiumtetraborate matic petroleum hydrocarbon fraction obtained by sulfuranhydrous and 10% boric acid, (3) a commercially availdioxide extractionis found particularly satisfactory. The able flameproofing compositionconsisting of 88% creopreferred concentrates contain from to by weightsote and 12% tricresylarylphosphate (8.6% phosphorus), of each of thetwo difierent thiophosphorus compounds, and (4) a composition accordingto the present invention the total, of course, not exceeding the 90% byweight alconsisting of 10% by weight of the concentrate of Exreadymentioned. 30 ample I, and 90% by weight creosote.

The following compositions are illustrative of the in- The cribs are setup as hollow squares approximately vention: 4 ft. high. The cribs of the4% in. x 7 in. x 40 in. pieces TABLE I Composition ggg ggggg PercentCompound (1) Percent Compound '(2) Percent 1 {Diesel Fuel Oil 90.0 }Zincditetradecylphenyl di- 4.25 Turpentine ms. Re- 4. 25

Pentachlorophenol.. 1. 5 thiophosphate. action Product. 2.. Creosote90.0 Zinc butyl hexyl dithio- 1.0 Pinene-P s Reaction 9.0

phosphate. Product. 3 Grade 1 Naphthenic 85.0 Zinc didodecyl dithiophos-10.0 5,0

Fuel Oil. phate. 4. Diesel Fuel 90.0 )Zincbutylamyldithiophos- 2.5 do2.5

. Pentachlorophenol. 5. 0 phate. 6 Creosote 80.0 Zinc dodecylphenylhexyl 18.0 Turpentine-P15 Re- 2.0

dithiophosphate. action Product. 6 No. 2Furnace Oil-- 95.0 Zine methylethyl dithio- 2.0 Pinene-PzS; Reaction 3.0

phosphate. Product. 7 Water 85.0 Zinc ditetradecylphenyl dl- 5.0Turpentine-P 5; Re- 6.0

thiophosphate. action Product. 8 Creosote 90.0 Zinfilgutyl amyldlthiophos- 10.0

p a e. n n 90.0 Plume-Pisa Reaction 10. 0

Product. 10 Boiled Linseed 011.... 90.0 Zingb utyl amyl dithlophos- 5.0n 6.0

p a e.

The effectiveness of the flameproofing compositions according to thepresent invention is further illustrated by the following examples. Inthese examples, the proportions unless otherwise specified are given onaweight basis:

Example I A flameproofing composition is prepared consisting of 90% byweight of creosote and 10% by weight of a typical concentrate of acombination of thiophosphorus compounds as described above. In thisinstance, the concentrate consists of 42.5% by Weight of Zinc butylhexyl dithiophosphate, 42.5% by weight of phosphorus pentasulfide anda-pinene reaction product and 15% by weight of amedium boiling liquidaromatic petroleum'hydrw carbon S0 extract. The flameproofingcomposition thus 75 The results of the tests are given in the followingtable.

are open on top while the cribs of the 4 x 4 and 2 x 4s are closed ontop. The ignition is by means of a gasoline fire. In the testing of the4% x 7 pieces, an aluminum pieplate with /2 pt. of gasoline set in thecenter of each crib and the 2 cribs tested together are ignited at thesame time. In the 4 x 4 cribs,the gasoline is held in 1 qt. cans forabout 2 minutes, at which time the cans are tipped over to ignite thewood. Temperatures reached in the fire are measured and go 'as high asabout 2,000 F. after about 10 minutes down to about 200 F. after 40minutes of burning time. In the tests, the time for the fire to go outis measured, as well as the time for any collapse of the timbers. Theweight of the remainders of the pieces after scraping oft" char is alsomeasured.

TABLE 11 Time (min) For Fire To Go Out Or To Collapse of Crib CreosoteOr Solution, lbs./ cu. it.

Percent Treatment Composition 100 Collapsed 104.

Out in 45'. 42 Do.* 34 Out in 33.

. 2-4 x 4 x 24" pieces 4 Collapsed. 23. 0 Out in 34'. 22. 7

100 27 28 Out in 29.

Retention, Pounds per cu. ft..." Wood Burning, Minutes Weight BeforeBurning, 1b.. Weight After Burning, l Weight Lost, Pounds Wind, mph

Depth of Char inches No. of Panels Treated-.

. 3-2 x 4 x 24 pieces Collapsed Collapsed 48. Collapsed 66.

Very small flames remained at end of a few places.

It is readily seen from the above test results that the thiophosphateflameproofing compositions of this invention are remarkably moreefiective than commercial compositions presently in use. The need forflameproofing compositions is clearly shown in the test results. Woodtreated with wood preservative oil alone such as the creosote iscompletely consumed in the test. Employing the flameproofingcompositions of this invention, it is seen that a substantial amount ofthe fiameproofer is retained by the treated wood, there is less weightlost in the wood and the flames burn themselves out and the fire isselfextinguished in a shorter period of time. Thus in each of the threecritical evaluations of the effectiveness of typical flameproofingagents, the compositions of the invention are found to be superior.

Example II In this example, the widely accepted panel fire test isemployed to evaluate flameproofing compositions according to thisinvention. In the tests, analogous fiameproofing compositions employingthe two difierent thiophosphorus compounds separately and in combinationare carried out to show the efiectiveness of the compositions. Theimprovement obtained when the thiophosphorus compounds are employed incombination in accordance with a preferred embodiment of the presentinvention is also shown.

Douglas fir panels are made up of three pieces of 2 in. x 10 in. x 14ft. long wood and two pieces of 2 in. x 6 in. x 14 ft. long. The panelsare treated under the usual temperature and pressure conditions with 10%by weight of each flameproofing agent in a 50: 50 mixture of creosoteand residual fuel oil (topped naphthenic crude). The panels are allowedto weather for a period of at least days. Following this, the panels areinstalled as part of the flooring in a mock-up railroad trestle section.The burning of the panels is accomplished by the ignition of tumbleweedstacked tightly under the trestle section. During the burning,temperatures between about 1500 F. and. 1600 F. are reached.

The following table shows the results of the tests. In Com-position No.1, the fiameproofing agent added to the 50:50 creosote and residuel fuelis by weight alphapinene and phosphorus pentasulfide reaction product incombination with 15 by weight of medium boiling petroleum aromatichydrocarbon extract. The agent of Com- 7 position No. 2. is 85% byweight zinc butyl hexyl dithio- The above test results show conclusivelythat remarkable fiameproof properties are obtained by treatment with thecompositions according to the invention.

It will also be seen iirom the test results that Composition No. 3 inparticular containing the combination of thiophosphorus compounds inaccordance with the preferred embodiment of the invention issurprisingly superior to Compositions 1 and 2 containing the singlethiophosphorus compounds. Considerably more of Composition 3 is retainedin the wood compared to Compositions 1 and 2. The burning time isdefinitely shorter and the weight loss of the wood due to burning isapproximately 30% less than the best of the other two compositions,namely Composition No. 2.

I claim:

1. A composition for flameproofing consisting essentially of woodpreservative oil and from about 5 to 30% by weight of the combination of(1) reaction product of phosphorus pentasul-fide and pinene and (2) zincdithiophosphate selected from the group consisting of Zinc dial-kyldithiophosphate containing from 3 to 8 carbon atoms in each of the alkylgroups and zinc dialkylphenyl dithiophosphate containing from 14 to 24carbon atoms in each of the alkylphenyl groups, said combinationconsisting of from 10 to by weight of reaction product and from 10 to90% by weight of zinc dithiophosphate.

2. A composition for flameproofiing consisting essentially of woodpreservative oil and from about 5 to 30% by weight of the combination of(1) reaction product of phosphorus pentasul-fide and alpha-pinene and(2) zinc butyl hexyl dithiophosphate, said combination consisting offrom 10 to 90% by weight of reaction product and from 10 to 90% byweight of zinc dithiophosphate.

3. A concentrate useful in the preparation of wood flameproofingcompositions, said concentrate consisting essentially of a liquidpetroleum hydrocarbon aromatic extract and from about 60 to 90% byweight of the combination of (1) reaction product of phosphoruspentasulfide and pinene and (2) zinc dithiophosphate selected from thegroup consisting of zinc dial'kyl dithiophosphate containing from 3 to 8carbon atoms in each of the alkyl groups and zinc dialkylphenyldithiophosphate containing from 14 to 24 carbon atoms in each of thealkylphenyl groups, said combination consisting of from 10 to 90% byweight of reaction product and from 10 to 90% by weight of zincdithiophosphate.

References Cited in the file of this patent UNITED STATES PATENTS2,344,393 Cook et al. ...a Mar. 14, 1944 2,358,305 Cook et al Sept. 19,1944 2,368,000 Cook et a1. Ian. 23, 1945

1. A COMPOSITION FOR FLAMEPROOFING CONSISTING ESSENTIALLY OF WOODPRESERVATIVE OIL AND FROM ABOUT 5 TO 30% BY WEIGHT OF THE COMBINATION OF(1) REACTION PRODUCT OF PHOSPHORUS PENTASULFIDE AND PINENE AND (2) ZINCDITHIOPHOSPHATE SELECTED FROM THE GROUP CONSISTING OF ZINC DIALKYLDITHIOPHOSPHATE CONTAINING FROM 3 TO 8 CARBON ATOMS IN EACH OF THE ALKYLGROUP AND ZINC DIALKYLPHENYL DITHIOMHOSPHATE CONTAINING FROM 14 TO 24CARBON ATOMS IN EACH OF THE ALKYLPHENYL GROUPS, SAID COMBINATIONCONSISTING OF FROM 10 TO 90% BY WEIGHT OF REACTION PRODUCT AND FROM 10TO 90% BY WEIGHT OF ZINC DITHIOPHOSPHATE.